1. Field of the Invention
The present invention relates to a communication terminal device and, more particularly, to a communication terminal device whose power consumption is reduced, for example, by controlling a backlight function of a display unit or the like.
2. Description of the Related Art
With recent advances in data communication techniques, integration techniques and packaging techniques, improvement in performance and reduction in size and weight of communication terminal devices have been accelerated. Typical of such devices are, for example, a portable telephone capable of conducting voice transmission and reception by mobile radio communication and a portable information terminal capable of reading various kinds of contents on the Internet in which computer networks are connected to each other. Among these communication terminal devices, portable telephones in particular have been enjoying a remarkable spread to provide various kinds of data communication services such as sending and receiving of electronic mail by accessing a data communication network such as the Internet and reading of contents. With communication terminal devices, therefore, users have more chances to use electronic mail service and contents reading other than ordinary mobile telephone services to have more and more chances of using data communication.
Under these circumstances, although with the progress in integration techniques and packaging techniques, reduction in power consumption of communication terminal devices has been enhanced as described above, a small-sized battery capacity hinders the reduction, so that time allowed to use the devices is inevitably shortened. Further reduction is strongly demanded in power consumption of communication terminal devices driven by batteries.
In general, communication terminal devices consume large part of electric power in a radio communication function and a backlight function or a sidelight function for lighting a liquid crystal display (hereinafter referred to as LCD) as a display unit or a switch (hereinafter referred to as SW). Therefore, reducing power consumption in both of these functions will be effective measures for low power consumption. As these measures, various techniques have been proposed related to, for example, lighting control of a backlight or a sidelight. In such a backlight function or a sidelight function, the higher the frequency of the above-described data communication becomes, the more the power is consumed because users' time of watching an LCD is increased. Accordingly, by appropriately controlling these functions, reduction in power consumption can be more efficiently achieved.
FIG. 14 shows an outline of a structure of a communication terminal device which conducts conventionally proposed backlight control. Assume here that the communication terminal device is a portable telephone. The communication terminal device includes an SW10 for receiving input of various kinds of instructions to the device as operation information, an operation detection unit 11 for detecting operation input by the SW10, a backlight 12 for lighting an LCD as a display unit not shown, a driver 13 for driving the backlight 12, a timer unit 14 for counting a lighting time of the backlight 12, a call detection unit 15 for detecting the communication terminal device being on the phone or not, and a control unit 16 for controlling each unit of the communication terminal device.
The control unit 16 of such a communication terminal device as described above is designed to have a central processing unit (hereinafter referred to as CPU) not shown to execute lighting control of the backlight 12 based on a control program stored in a predetermined storage device such as a read only memory (hereinafter referred to as ROM).
FIG. 15 shows an outline of processing contents of a control program stored in a predetermined storage device of the control unit 16. Prior to the processing by the control program, a predetermined backlight lighting time is set at the timer unit 14 in advance and a lapse of the backlight lighting time is notified as time out. First, the control unit 16 controls the operation detection unit 11 to monitor operation/non-operation by the SW10 (Step S20: N) and when the operation is detected (Step S20: Y), sends out a control signal to the driver 13 to light the LCD not shown which is to be displayed according to predetermined display information and start lighting of the backlight 12 (Step S21), as well as starting counting the timer unit 14. Subsequently, the control unit 16 controls the call detection unit 15 to detect the communication terminal device being on the phone or not (Step S22) and when detecting the device being not on the phone (Steps S22: N), determine whether time out is notified which indicates that the time counted by the timer unit 14 overs the above-described backlight lighting time (Step S23). If no determination is made here that time out is notified (Step S23: N), return to Step S22 to detect the communication terminal device being on the phone or not again. When at Step S23 the determination is made that time out is notified (Step S23: Y), turn off the backlight 12 through the driver 13 (Step S24) and return to Step S20 to monitor the SW operation again (return).
When at Step S22 the communication terminal device is detected being on the phone by the call detection unit 15 (Step S22: Y), turn off the backlight 12 through the driver 13 (Step S25). Subsequently, monitor completion/incompletion of the being on the phone state detected by the call detection unit 15 at Step S22 (Step S26: N) and when the completion is detected (Step S26: Y), return to Step S21 to again turn on the backlight 12 through the driver 13.
Thus, when operation by the SW10 is detected by the operation detection unit 11, monitor a start of a call and when the start is not detected, turn off the backlight after a lapse of a predetermined backlight lighting time. In addition, when the start of a call is detected, turn off the backlight immediately and upon completion of the call, turn on the backlight again. Such arrangement prevents wasteful consumption of battery power by turning off the backlight during a call when neither the SW10 nor the LCD not shown can be visually observed.
One of such techniques related to communication terminal devices as described above is disclosed, for example, in Japanese Patent No. 2891935, entitled “Portable Telephone Set”.
According to a technique related to a communication terminal device which conducts backlight lighting control disclosed in, for example, Japanese patent Laying-Open (Kokai) No. Heisei 5-344022, entitled “Portable Data Communication Device”, after data communication is started, first a backlight lighting flag is reset to check whether the backlight is lighting or not at that time point and when it is lighting, the backlight lighting flag is set and once stored in a memory. Thereafter, turn off the backlight and after the data communication is finished, the backlight is turned on according to the backlight lighting flag stored in the memory.
As described in the foregoing, recent communication terminal devices enable not only conventional “call” by voice but also reception of data of contents described in a predetermined information description language such as a hypertext markup language (hereinafter referred to as HTML) by a direct access to the Internet and reading of the contents on a display screen such as an LCD. Typical of such devices are, for example, “i-mode” by NTT DoCoMo Inc. and a wireless application protocol (hereinafter referred to as WAP) system. Communication terminal devices for use in such systems include a CPU having high processing power and execute a browsing function for reading contents data described in Compact HTML similar to HTML or wireless markup language (hereinafter referred to as WML). Also for a communication terminal device having such a browsing function, the above-described backlight lighting control, rather than lighting of the backlight all the time after communication is started, is effective in reducing power consumption of the device.
However, in the communication terminal device shown in FIG. 14, the backlight is turned on upon completion of a call and in the communication terminal device to which the technique disclosed in Japanese Patent Laying-Open (Kokai) No. Heisei 5-344022 is applied, if the backlight is lighting at the start of communication, the backlight is turned on upon completion of the communication. In a case of the above-described communication terminal device which executes a browsing function, however, there is a time difference between the end of the communication function and the end of processing of data readable on the display unit such as an LCD through execution of the browsing function, so that there occurs a case where even if the backlight is turned on as soon as the communication function ends, no readable contents are displayed on the display unit. In other words, since the device is designed to turn on the backlight immediately upon completion of the communication function, from the time of turn-on of the backlight until when contents are made readable on the display unit by the browsing function, useless electric current for lighting the backlight will be consumed.
On the other hand, in a WAP system, communication is conducted based on a transmission and reception unit called “DECK” made up of a plurality of small contents called “CARD” in order to increase communication efficiency. Assuming, for example, that three screens of “CARD” approximately equivalent to one screen on the display unit of the communication terminal device make one “DECK”, reception of three screens of contents data is conducted by one communication. With the communication terminal device shown in FIG. 14 and the communication terminal device to which the technique disclosed in Japanese Patent Laying-Open No. Heisei 5-344022, accordingly, although the contents of the first screen are received and browsing as data processing is finished by the browsing function to complete a screen to be displayed on the display unit such as an LCD, no backlight lighting is conducted unless reception of all the contents of three screens is completed. Until then, no user is allowed to read the contents. In other words, reducing a lower consumption results in degrading users' ease of use and therefore demanded is a communication terminal device whose power consumption is reduced appropriately without degrading users' ease of use.